The present invention relates to a drive system for a water lance blower for cleaning a heating installation having wall areas and a hatch, wherein the heating installation is operational with flames and/or smoke flowing therethrough. The invention further relates to a method for operating a water lance blower comprising moving the water lance by at least one movement element along pre-calculated lines of movement at pre-calculated variable speeds dependent upon position.
The cleaning of heating installations, in particular of furnaces of high powered steam boilers during operation takes place inter alia with the aid of water lance blowers, which supply a focused water jet through the furnace onto the wall lying opposite. As a result of the thermal shock occurring, the kinetic water jet energy and of the sudden vaporisation of water forced into the pores of the deposits, peeling off of the dirt composed of rust, slag and ashes is effected. Typical arrangements and the associated field of such water lance blowers are described, for example, in DD 276 335 A1, DD 281 452 A5 and DD 281 468 A5.
The water jet from water lance blowers generally follows a specific predetermined path onto the surface to be cleaned, also known as the blowing pattern, wherein this path is generally wave-form or spiral and where appropriate avoids obstacles, apertures or other sensitive areas.
In addition to control of the drive systems by means of a template, which inevitably produces a very specific blowing pattern, mainly dual axis controls are fitted with axes of control at right-angles to one another, in particular a horizontal and a vertical axis, in order to be able to control wave-form paths particularly easily. In this manner, it was always possible until now to produce specific wave-form blowing patterns purely by means of time control or control of the individual axial drives from a minimum impact to a maximum impact.
This type of control makes it necessary, however, to align the drive system as precisely as possible as is described, for example, in DD 234 479 A1. Here, two actuating elements act upon the water lance, wherein these two actuating elements are arranged at an angle of 90.degree. on a frame, wherein in addition the fixing points of the actuating elements must lie in a plane with the point of movement of the water lance.
A further dual axis control is also known from WO 93/12398, which precisely controls the water lance by means of two spindle mechanisms running perpendicularly to one another.
It is also known from DD 239 656 A1 to control the cleaning parameters of a water lance blower by means of temperature measurements of the surface to be cleaned.
Lastly, it is also known from DE 33 43 992 C1 that water lance blowers can be provided with a housing, in order to prevent uncontrolled gas exchange through the hatch and to protect the water lance and movable parts from soiling.
The previously known water lance blowers have the disadvantage that the guidance of the blower lance takes place by means of complex mechanisms and central drives, wherein in the space around the blowing guides drive and bearing elements are supported and arranged in a bulky frame construction, take up a large amount of space, and inhibit the ability of the lance to move and allow the supply of water only from the rear. Consequently there is a long water supply path with a hose connection which inevitably has to be connected from the rear to the end of the blower pipe. The consequently large lengths of the lance and the water supply necessary leads to large leverages and forces which in turn necessitate substantial guides, drives and frames.
In addition there is not always enough space available in the area of every hatch in which a water lance blower ought advantageously to be arranged. Numerous interior components, such as steam pipes, switchgear cupboards, working platforms and so forth, impede the attachment of large rectangular frameworks.
This problem is exacerbated when the water lance blower has to be provided with a housing and a supply of blocking and flushing medium for prevention of uncontrolled gas exchange through the hatch. As the pressure in a heating installation varies, there are both operating conditions in which air from the outside is sucked into the installation through the hatch and the swivel joint of the water lance and operating conditions where smoke, ash and waste gases reach the outside through the hatch and the joint. Both are undesirable, wherein the latter damage the water lance and the joint and can reduce their useful life. Known systems with housings for blocking and flushing medium are moreover set out such that in all operating conditions no gas can flow from the heating installation into the housing, which means, however, that in many cases there is an excessive supply of blocking and flushing fluid to the heating installation, which is also disadvantageous.